The correct answer is to manually change the primary email address for each user to user@contoso.com in the Microsoft 365 admin center. This is required because adding and verifying a custom domain only makes it available for use; it does not automatically update existing users’ default onmicrosoft.com addresses. Each user’s User Principal Name (UPN) and primary SMTP address must be individually edited under Users > Active Users by selecting a user, then modifying the username and email fields to reflect the custom domain. On the MS-102 exam, this scenario tests your understanding of post-domain-verification configuration steps, and a common trap is assuming that adding the domain alone will propagate changes to all users. Remember the key distinction: domain verification enables usage, but manual user updates complete the migration. A helpful memory tip is “Verify the domain, then verify each user’s address”—you must touch every account to switch the primary email domain.
MS-102 Deploy and manage a Microsoft 365 tenant Practice Question
This MS-102 practice question tests your understanding of deploy and manage a microsoft 365 tenant. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
You are a Microsoft 365 administrator for a small business with 50 users. The company is using Microsoft 365 Business Basic. You need to configure email for the custom domain contoso.com. You have added the domain in the Microsoft 365 admin center and verified ownership. Users currently have onmicrosoft.com email addresses. You need to change the primary email address for all users to their custom domain (e.g., user@contoso.com). What should you do?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "primary"
Why it matters: Asks for the main purpose or function, not a secondary benefit. Eliminate answers that describe side-effects or partial functions.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Change the primary email address for each user to user@contoso.com in the admin center.
Option C is correct because in Microsoft 365, after adding and verifying a custom domain, you must manually update each user's primary email address (User Principal Name and primary SMTP address) from the default onmicrosoft.com domain to the custom domain. This is done in the Microsoft 365 admin center under Users > Active Users, by editing the username and email fields. Simply adding the domain does not automatically change existing user addresses.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
Remove the onmicrosoft.com domain from the tenant.
Why it's wrong here
You cannot remove the initial domain.
✗
Convert all mailboxes to shared mailboxes and reassign licenses.
Why it's wrong here
Unnecessary.
✓
Change the primary email address for each user to user@contoso.com in the admin center.
Why this is correct
After domain verification, you can update user email addresses.
Clue confirmation
The clue word "primary" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
Configure the MX record for contoso.com to point to Exchange Online.
Why it's wrong here
MX record is needed for email delivery, but not to change the email address.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates assume adding and verifying a custom domain automatically updates existing user email addresses, when in fact it only makes the domain available for use, requiring manual or scripted updates per user.
Detailed technical explanation
How to think about this question
When a custom domain is added and verified, Microsoft 365 treats it as an accepted domain, but existing user objects retain their original UPN and primary SMTP address (e.g., user@contoso.onmicrosoft.com). The change must be made via Set-MailUser or Set-MsolUserPrincipalName in Exchange Online PowerShell, or through the admin center UI, which updates the proxyAddresses attribute and sets the primary SMTP address to the custom domain. Without this step, mail flow to the custom domain will fail even if DNS records are configured.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A cloud solutions architect for a retail company is evaluating services for a new workload. The correct answer here reflects best practice for the specific scenario described — not a general cloud recommendation. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Cloud exam questions reward reading the constraint carefully: the same technology can be right or wrong depending on the use case.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this MS-102 question in full detail.
Deploy and manage a Microsoft 365 tenant — This question tests Deploy and manage a Microsoft 365 tenant — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Change the primary email address for each user to user@contoso.com in the admin center. — Option C is correct because in Microsoft 365, after adding and verifying a custom domain, you must manually update each user's primary email address (User Principal Name and primary SMTP address) from the default onmicrosoft.com domain to the custom domain. This is done in the Microsoft 365 admin center under Users > Active Users, by editing the username and email fields. Simply adding the domain does not automatically change existing user addresses.
What should I do if I get this MS-102 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "primary". Asks for the main purpose or function, not a secondary benefit. Eliminate answers that describe side-effects or partial functions.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
This MS-102 practice question is part of Courseiva's free Microsoft certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the MS-102 exam.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.